2.3 Effect of Bioaccumulation on Ecosystems

2.3 Effect of Bioaccumulation on Ecosystems

Role of Amphibianslive on both land and in the water.sensitive to chemical changes in the environmentSince the 1980s, many amphibian species have suffered declines in population.alarming increases in amphibian birth deformities.Many theories attempt to explain these changes, including drought, increased UV rays, pollution, habitat loss, parasites, and diseases.

Pollutants and the Food ChainHuman activities can make natural disturbances much worse Introduced synthetic (human made) chemicals into the environment

What is Bioaccumulation?Bioaccumulation: gradual build-up of chemicals in living organisms Occurs when chemicals are taken up/stored faster than they can be broken down/excreted Absorbed through food, skin contact, or respiration

Chemicals can affect the nervous, immune, and reproductive systems in animals Ex. birth defects, inability to reproduce Keystone Species: species that can greatly affect population numbers and an ecosystems health

SalmonFood source for bears, wolves, eagles, etc.Source of nutrients as they decay

What is Biomagnification?Biomagnification: chemical that accumulate AND become more concentrated at each trophic level chemicals are passed on as they are eaten and digested

Red TidesProduce toxic chemicals that affect clams, mussels, and oystersToxins bioaccumulate to a level that is poisonous for larger animals

PCBs and OrcasPCB: polychlorinated biphenylsSynthetic chemicals used from the 30s-70s in industrial products Have long half-lives (the amount of time it takes to decay) Affects reproduction in orcas May last until 2030Newborn calves have high levels of PCBs, even though theyve been banned for decades

Persistent Organic PollutantsPersistent Organic Pollutants (POPs): carbon-containing compounds that remain in water and soil for many years Includes PCBsEx. insecticide sprays

DDT (dichlorodiphenyl trichloroethane): meant to control mosquitoesBanned because of biomagnification, long half-life, and presence in environment

Accumulation measured in parts per million (ppm)1 ppm = 1 particle mixed with 999,999 other particles DDT toxic at 5ppmHeavy MetalsMetallic elements with a high density that are toxic at low concentrationsDont degrade and cant be destroyed Some are essential to the human body in small quantitiesCopperZinc

3 of the worst heavy metals are lead, cadmium, and mercury!LeadNaturally present in all soils but levels have increased Used in insecticides, paints, and gas; now found in electronics not considered safe at ANY levelCan be ingested, absorbed, or inhaled Can cause anemia, nervous system damage, reproduction difficulties, and impaired mental development

CadmiumFound in the Earths crustReleased through weathering, volcanoes, and forest fires Used in plastics manufacturing and rechargeable batteries Enters soil through zinc production and phosphate ore mining Toxic to earthworms and negatively impacts fish (higher death rates, lower reproduction rates)

Major source of Cadmium poisoning: SMOKING (tobacco absorbs it)Causes lung cancer Moves through the digestive system liver kidneys Leads to infertility and damage to the central nervous system, immune system and DNA

MercuryReleased naturally (volcanoes, weathering, etc.)Levels dramatically increased due to fossil fuels, mining, industrial uses (batteries), etc.Coal burning accounts for 40 percent of the mercury released into the atmosphere.Falls as rain and dust, then binds to soil Mercury bioaccumulates in the brain, heart and kidneys of many animals

Reducing the Effects of Chemical PollutionMethod 1: Trap contaminant in soil Example: phosphate fertilizer is added to lead contaminated soil By trapping chemicals in the soil, they cannot enter the food chains as easily

Method 2: Bioremediationthe use of micro-organisms or plants to help clean up toxic chemicalsExample: the oil industry uses bacteria to eat oil spills